Authorities say an eastern Iowa woman was killed when a homemade cannon exploded at a backyard gathering, the AP reports. Davenport television station KWQC-TV reports that 55-year-old Lori L. Heims of Edgewood was flown to an Iowa City hospital, where she was pronounced dead. The Delaware County Sheriff's Department says Heims was injured at the gathering with friends in Greeley around 11:40pm Saturday. Investigators say the cannon was loaded and fired, and when it went off, the rear portion of the barrel blew out and sent fragments toward Heims. One of the fragments struck Heims in the head. (More cannon stories.)